FDA Advisers Back a Multi-Cancer Blood Test, but Follow-Up Capacity Lags

For a decade, the promise of a single blood draw that screens for dozens of cancers has lived mostly in investor decks. Last week it moved a step closer to routine care. On September 23, the FDA's Molecular and Clinical Genetics Devices Panel voted 7-2 with one abstention that the benefits of GRAIL's Galleri test outweigh its risks. The vote on effectiveness was much closer, at 6-4. That gap between enthusiasm and certainty is the story, because approval is not where multi-cancer screening succeeds or fails. It succeeds or fails in the weeks after a positive result, when a patient needs imaging, a specialist and an answer. The system that has to deliver that answer is already stretched.

What the Panel Actually Endorsed

Galleri is a next-generation sequencing test intended as a prescription-only screen for adults aged 50 and older, and it has held FDA Breakthrough Device designation since 2018, according to The ASCO Post. The committee vote is not binding, and GRAIL says it expects a final decision on its premarket approval application in the coming months. Investors did not wait: STAT reported that GRAIL shares jumped 33% on the Monday the FDA's briefing documents went public.

The strongest evidence came from North America. In the PATHFINDER 2 study, published in Nature Medicine and summarized by OHSU, 35,878 adults across the US and Canada were screened. The test returned 287 cancer signals, and 173 of those people were diagnosed with cancer, a positive predictive value of 60.3%. Specificity was 99.64%, meaning a false-positive rate of 0.36%, and the test predicted where the cancer sat in the body 91.3% of the time. Nearly half of the cancers were found at stage I or II, and about 70% were types with no recommended screening at all. OHSU principal investigator Dr. Nima Nabavizadeh framed the test as "a powerful complement" to standard screening, not a replacement.

Why the Effectiveness Vote Was Split

The caution has a source. The randomized NHS-Galleri trial in England, which enrolled 142,250 people across three annual screening rounds, did not meet its primary endpoint of reducing combined stage III and IV cancers. Stage IV incidence ran roughly 14% lower in the screened group, but that finding could not be formally tested once the primary endpoint failed. The companion analysis put sensitivity for diagnosed cancers at just 27% to 37%, and positive predictive value fell from 58% in the first round to 46% by the third. An accompanying NEJM editorial concluded the test is not yet ready for population-wide screening.

Panelists said as much. Healio reported that Dr. Victor van Berkel called false reassurance "the largest issue," since a negative result can be misread as ruling cancer out, and Dr. Stanley Lipkowitz abstained on the grounds that the data did not yet show clinical effectiveness. Dr. Daniel Swerdlow raised a different problem, one that sponsors and health systems should weigh most heavily: shortages of the radiologists and endoscopists needed to run confirmatory imaging and procedures after a positive test.

The Bottleneck Moves Downstream

The per-patient burden looks manageable. Only 0.6% of PATHFINDER 2 participants underwent an invasive procedure after a positive result, and most of those procedures were nonsurgical. The problem is scale. A test that finds 6.5 times more cancers than standard screening, most of them in organs no program currently screens, generates a stream of patients who each need a diagnostic pathway that often does not exist yet. A positive signal pointing to the pancreas or the liver is only valuable if a scan and a specialist are available within weeks, not months.

Coverage is the other half of the equation. The Nancy Gardner Sewell Medicare Multi-Cancer Early Detection Screening Coverage Act was signed into law on February 3, 2026, creating a pathway for CMS to cover FDA-approved tests without affecting existing screening benefits. Medicare coverage can begin in 2028, WALB reported. That leaves commercial payers and self-insured employers roughly two years to decide whether to cover a test whose mortality benefit is unproven, and to model what a wave of positive results would cost downstream. Dr. Toni Choueiri noted at the meeting that coverage decisions by Medicare and private insurers remain uncertain.

A Playbook for Sponsors, Health Systems and Payers

• Build the diagnostic pathway before the launch. Map who receives a positive result, who orders the imaging, and how fast a patient reaches a specialist for each predicted cancer origin.
• Plan imaging and endoscopy capacity explicitly. The panel's workforce warning is a planning input, not a footnote. Forecast confirmatory volume from the 0.54% detection rate seen in PATHFINDER 2 and staff to it.
• Train primary care on negative results. A test that misses most cancers in some settings cannot be treated as an all-clear. Clinician education on false reassurance belongs in every rollout plan.
• Keep guideline screening intact. Messaging should position multi-cancer testing as an addition to mammography, colonoscopy and lung screening, never a substitute.
• Model coverage against real disease burden. Payers deciding before the 2028 Medicare start should estimate prevalence in their own membership, not rely on trial populations.
• Generate outcome data now. The unresolved question is mortality. Sponsors that fund implementation and registry studies during early adoption will shape how CMS reads the evidence.

The advisory vote marks a real milestone for early detection, and the PATHFINDER 2 numbers show a test that finds cancers nothing else is looking for. But the panel's split verdict is a reminder that detection is the easy part to measure. The harder test will be whether the imaging suites, specialists and benefit designs behind the blood draw can keep up with what it finds.